Control mechanism for automatic phonographs



April 1944' J. H. PRESSLEY 4 2,345,684

CONTROL MECHANISM FOR AUTOMATIC PHONOGRAPHS Filed Oct. 9, 1941 AMPLIFIER23 FIG. 3

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AMPLIFIER 'INVENTOR QACKSOP H. PR ESSLEY appended claims.

Patented Apr. 4, 1944 UNITED STATES PATENT OFFICE CONTROL MECHANISM FORAUTOMATIC PHONOGRAPHS V Jackson Hard Pressley, Marion, 1116., minor to IFarnsworth Television and Radio Corporation, a corporation oi DelawareApplication October 9, 1941, Serial No. 414,242 Claims. (Cl. 192118)This invention relates to control mechanism for automatic phonographsand more particularly to that type of control mechanism adapted to beactuated by the variation ofthe speed of movement of the pickup arm.

According to conventional automatic phonograph apparatus. the controlmechanism is actuated by a mechanical movement of levers or by amechanical closing of an electric circuit. The mechanical movement oflevers is brought about 'either as. a result of the pickup arm reachinga predetermined position from the center of the turntable or by anabnormal movement of the pickup arm when it reaches the tripping grooveof a record on the turntable.

The object of the invention is to provide an improved and simplifiedcontrol mechanism adapted to initiate the operation of a drivingmechanism in an automatic phonograph.

Another object of the invention is-to provide a control mechanism whichwill generate a signal as a result of the abnormal movement of thepickup arm when it reaches a tripping groove of a record on theturntable.

Another object of the invention is to provide a control mechanism whichwill regulate a signal in response to the abnormal movement of a pickuparm for initiating the operation of a driving mechanism.

Another object of the invention is to provide comprising a trippingmechanism for controlling the operation of the driving means, means re-'sponsive to an electric control signal for actuating the trippingmechanism, means operably' connected with the pickup arm and responsiveto movement thereof at the second difierent speed for developing thecontrol signal, and means for applying said control signal-to saidactuating means.

, For a better understanding of the invention,

together with other and iurther objects thereof, reference is made tothe following description taken in connection with the accompanyingdrawing and its scope will be pointed out in the In the accompanyingdrawing:

Fig. 1 is a side view showing one form of the control mechanism;

Fig. 2 is a detail view along line 2-2 of Fig. 1;

Fig. 3 is a side view showing another form of the control mechanismshown in Fig. 1;

Fig. 4 is a sectional view along lines 4-4 of Fi 3; and

Fig. 5 is a plan view of the tripping mechanism adapted to be operatedby the control mechanisms shown in Figs. 1 and 3.

Referring now more particularly to Figs. 1 and 3, the apparatusillustrated includes a base plate ID, to which a turntable l I isrotatably connected in a suitable manner. At one side of the turntableii, there is affixed to the base plate ID in a suitable manner apedestal l2 which is adapted pivotally to support at its upper end apickup arm l3. At the free end of the pickup arm l3, there is provided areproducer H with a stylus Hi. When the stylus i5 is tracking a playinggroove of a disc record is on the turntable H, the pickup arm I3 isadapted to move at a pre-- determined speed toward the center of theturn. table. When the stylus I5 is tracking a tripping roove of a recordIE, it is adapted to move the pickup arm 13 at more than thepredetermined speed toward the center of turntable ll. Fixed to thepivotal end of the pickup arm l3, there is a shaft ll which extendsdownwardly through the pedestal l2 and is adapted to rotate as thepickup arm l3 moves radially across the turntable ll.

One form of control mechanism adapted to be operated with the pickup armI3 is illustrated in Fig. 1. It includes a condenser I8, which comprisesa set of fixed plates 19 connected to the bottom of the base plate to ina suitable manner, preferably by a bolt 20, and a set of movable plates2l connected to the lower end of the shaft ll to move therewith. The twosets of plates l9 and 2| are so related toeach other that the plate 2|may be moved between the plates 19, as is readily seen in Fig. 1. Whenthe pickup arm i3 is in the initial playi g groove of a record on theturntable II, the sets of plates 19 and 2| are in the p0siti0ns shown inFig. 2. When the pickup arm I3 moves at a predetermined speed toward thecenter of the turntable- 2| move in a clockwise direction at 111817greater speed.

8 re nd- The two sets of condenser plates as and ii are connected in anelectric circuit 22 which also includes a source or potential 23, and aresistance 25. The signal in the circuit 22 is amplified by a suitableamplifier 25. The amplified signal is used to control the operation ofan electro=magnet 28. The electro=magnet 28 is fixed to the bottom ofthe base plate id in a suitable manner,

as shown in Fig. 5.

According to the equation, EC=Q, disregarding the resistance 26, theelectric charge on the condenser it varies directly as its potential andmay also be expressed as follows:

c Fag,

Thus, it is seen that the current flowing in electric circuit 22 may becontrolled by the rate of change of the capacity in the condenser 88,.which is brought about by changing the speed of movement of the pickuparm it. Now, if the resistance 26 is reintroduced into the circuit 22,it is seen that any change in the current flowing in the resistance 2%will produce a proportionate change in the potential drop across theresist- .ance it. Thus, the change of the speed of the pickup arm 63 hasthe same proportional efiect on the potential drop across the resistance24 as it has on the current flowing in the circuit 22.

The change imparted to the signal in circuit 22 is utilized to initiatethe operation of a tripping mechanism, which will be describedhereafter.

Another form of control mechanism is shown in, Fig. 3 of the drawing. Itincludes a solenoid 29 which is supported from the bottom of the baseplate l6 in some suitable manner, as shown in Fig. 3. A small permanentmagnet 30, one end of which is pivotally connected to a lever 3i, isadapted to be moved in and out of the solenoid 29' in response to themovement of the pickup arm!3 toward and away from the center of theturntable. The other end of the lever 36 is swivelly connected to alever 32, as shown in Fig. 4. The opposite end of the lever 32 isfixedto the shaft ll,preferably as shown in Figs. 3 and 4. The magnet 38 isassociated with the solenoid 29 and the shaft ll in such a manner thatwhen the stylus of the pickup arm 53 is in, the initial playing grooveof the record on a position shown in and the armature assaes cuit 35which also includes an amplifier which serves the sameiunction as theamplifier 25 in the control mechanism described above and will bereferred to by the same number. As has been explained above, theamplified signal from the amplifier 25 is fedto'the electro-magnet 28 tocontrol its operation.

While only two -forr'ns of control mechanism have been illustrated anddescribed, it'is understood that any electrical control mechanism issuitable to initiate the tripping mechanism to be described hereafter,which is responsive to the variation of the speed of an element such asthe piekup arm I3.

The tripping mechanism, which is adapted to be'initiated by a signal ofpredetermined value from the control mechanism described above, in=eludes the electro-magnet 28, previously mentioned. A curvedrlever 35 ispivotally connected to the bottom of the base plate l8, preferably asshown in Fig. 5. .Provided near the free end of the lever 35 is aprojection 36 and an armature 37. A spring 38, connected in a suitablemanner to the base plate ill, is adapted to engage the projection 36 andmaintain the lever 35 in the- Fig. 5. The electro-magnet 28 37 are sorelated that when suficient current fiows into the electro-magnet Z8,itattracts the armature 3i and moves the lever 35 against the biasingaction of the spring 38. When the electro-magnet 28 is no longerenergized, the tension in the spring 38 moves the lever 35. back to theposition shown, in Fig. 5.

When the lever 35 is in the position shown in Fig. 5, it is adapted toengage one end of a pivotal lever 39. When the electro-magnet 28attracts the lever 35'i'nto engagement therewith, it

also moves the lever 35 out of engagement with the lever 38.Intermediate its ends, the lever 35? the turntable ii, the magnet 30 isin the position shown in-Fig. 4. When the pickup arm l3 is moved towardthe center of the turntable at a predetermined speed, the magnet 30 ismoved into the solenoid 29 at a corresponding speed. When the pickup armi3 is moved toward the center of the turntable H at a greater thanpredetermined speed, the magnet i moved into solenoid 29 ata'correspondingly greater speed. The voltage induced in the solenoid 2 9varies directly with the speed with which the magnet 30 is moved intothe solenoid 29 and with the speed with which the pickup arm I3 ismoved.

The solenoid 29 is included in an electric ciris pivotally connected toa cam wheel Q9, as shown in Fig. 5. The opposite end of the lever 39 hasa projection fill which is adapted to move into the path of a projectiont2 when the lever as is released by the lever 35. The projection 32 isrotatably connected to a continuously rotating shaft (53. The shaft Q3has aflixed thereto a pinion 56 which is adapted to-drive the cam wheelid. The cam whee1 630 is mounted to rotate on a shaft (is extendingdownwardly from the base plate in. The cam wheel may serve any suitablefunction, as, for example, moving records to a turntable and moving astylus of a pickup arm into and out ofengagement, with a record on aturntable. These last-mentioned functions are performed by the cam wheeld2 of U. S. Patent No. 2,012,185. The periphery of the cam wheel to hasa mutilated portion 5b which is adapted to break the drivingrelationship between the cam wheel 36 and the pinion dd when it is'movedopposite the periphery of the pinion M.

The general mode of operation of the appa-. ratus will now be described.After a record is placed on the turntable H and the stylus is in the.reproducer M of the pickup arm i3 is brought into engagement with theinitial playing groove of the record on the turntable, the rotation ofthe turntable is initiated. While the stylus i5 is tracking the playinggroove of the record on the turntable, the pickup arm 53 ismoving towardthe center of the turntable H at a predetermined speed. When the stylus65 moves into the tripping oove of the record on the turntable ii, thepickup 'arm moves toward the center or the record at a greater thanpredetermined speed.

The movement of the pickup arm 58 at .a pre- ,a predetermined speed doesnot have a suflicient efiect on the electric circuit 22 or the electriccircuit", respectively, to permit a suillcient ourgroove of a record,the combination of a tripping mechanism for controlling the operation ofsaid driving means; means responsive to an electric control signal foractuating said tripping mech- 5 anism; an electric circuit connected tosaid lastrent to flow in the electro-magnet28 to attract er thanpredetermined speed, has a suillciently great effect on the electriccircuit 22 or the electric circuit 34, respectively, to cause sufficientcuri5 rent to flow in the electro-magnet 28 to attract the armature 31.The attraction of the armature 31 by the electro-magnet 28 moves thelever 35 out of engagement with the lever .39. The disengagement of thelever 39 by the lever 35 permits the projection 4| of the lever 39 tomove into the path of the projection 42. When the projection 42 engagesthe projection 4|, the lever 39 and thecam wheel 40 are moved in ahorizontal plane relative to the pinion 44 sufliciently far to bring thecam wheel 40 into driving em gagement with the pinion 44. Thereafter,the cam wheel 40 is driven through one revolution, after whichit isbrought out of engagement with the pinion 44 by the mutilated portion46. As has been mentioned previously, the cam wheel 40, during itssingle revolution, may be adapted to serve the same function as the camwheel 62 of U. S. Patent No. 2,012,185, that is, to move a record to aturntable and move the stylus of a pickup arm out of and into engagementwith a record on the turntable. During .the movement of the cam wheel.40, the lever 35 engages the lever 39 so that the tripping mechanismmay again be initiated by the control mechanism.

Whfle there has been described what is at present considered thepreferred embodiment of the invention, it will be obvious to thoseskilled inthe art that various changes and modiflcationsmay be madetherein without departing from the invention, and it is, therefore,aimed in the appendmentioned means; a resistance-ti source of potentialand a capacitance device connected in series in said circuit, saidcapacitance device having a fixed member and a movable element operablyconnected with said pickup arm to be moved thereby and being adapted todevelop said control signal in response to the movement of said pickuparm at said second speed; and means for applying said control signal tosaid actuating means.

3. In an automatic phonograph, the combi nation of a pickup arm movableover a record. driving means adapted to be actuated by an electriccontrol signal, means for applying said control signal to said drivingmeans, and a capacitance device operably associated with saidsignalapplying means and having movable means operably connected withsaidpickup arm for'being .moved thereby to develop said control signalin response to a change in the rate of movement of said pickup armwhereby said driving means is fast speed as it follows the trippinggroove of a record, said pickup arm being mounted for pivotal movementon a shaft adapted to rotate with said pickup arm, a variable condenserhaving a set of stator plates mounted stationary with respect tosaid'shaft and a set of rotor plates mounted on said shaft for movementtherewith, an electrical circuit including a series arrangement of saidcondenser, a source of potential and o a resistor, said circuitfunctioning to develop ed claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What is claimed is: 1. In an automatic phonograph including drivingmeans and a pickup arm adapted to be moved driving means; meansresponsive to an electric voltages -in said resistor representative ofsaid two speeds of pickup arm movement, a tripping mechanism, and meanscontrolled by the voltage developed in said resistor representative ofsaid fast pickup arm movement for actuating said tripping mechanism.

5. In an automatic phonograph, a pickup arm movable at a relatively slowspeed as it follows a playing groove of a record and at a relativelyfast speed as it follows the tripping groove of a record, said pickuparm being mounted for pivotalmovement on a shaft adapted to rotate withsaid pickup arm, a variable condenser having a respect to said shaft,and a set of rotor plates control signal for actuating said trippingmechseries arrangement of said condenser, a source of anismrmeans,including a capacitance device having a fixed element and a movableelement operably connected with said pickup arm to be moved thereby, fordeveloping said control signal in response to the movement of saidpickup arm at said second speed; and means for applying said controlsignal to said actuating means.

2. In an automatic phonograph including driving means and a pickup armadapted to be moved at a first predetermined speed as it followsaplaying groove of a record and to be moved at a 7 second differentspeed as it follows a tripping mounted on said shaft for movementtherewith, whereby to vary the capacity of said condenser at a rate inaccordance with the speed of said pickup arm movement, an electricalcircuit including a said two speeds of pickup arm 'movement, a trippingmechanism, and means controlled by the voltage developed in saidresistor representative of said fast pickup arm movement for actuatingsaid tripp n mechanism.

Jackson HARD PRESSLEY.

